One-pack moisture-curing epoxy resin composition

ABSTRACT

A one-pack moisture-curing epoxy resin composition which can be cured at ordinary temperatures and is improved in storage stability without impairing the quickness of curing, i.e., is excellent in two properties incompatible with each other. This composition includes one ore more members selected from the group consisting of vinyl carboxylates of the general formula (1) and epoxy-containing silyl compounds of the general formula (2), one or more members selected from the group consisting of ketimines and oxazolidines, and an epoxy resin. (1) [In the general formula (1), R 1 , R 2 , R 3 , and R 4  are each independently hydrogen or an organic group; and n is an integer of 1 or above] (2) [In the general formula (2), R 5  and R 6  are each independently alkyl; R 7  is an epoxy-containing organic group; and n is an integer of 1 to 3]

TECHNICAL FIELD

The present invention relates to a one-pack moisture curable epoxy resincomposition having excellent curing properties and good storagestability. Particularly, the present invention relates to a one-packmoisture curable epoxy resin composition having excellent curingproperties and good storage stability and suitable as a one-packroom-temperature curable epoxy adhesive, one-pack room-temperaturecurable epoxy putty material, one-pack room-temperature curable epoxypaint, one-pack room-temperature curable epoxy coating material andone-pack room-temperature curable epoxy potting material.

BACKGROUND ART

An epoxy resin composition is excellent in physical strength andadhesion and has been widely used as an adhesive, putty material, paintand coating material. Since the conventional epoxy resin compositionuses a highly reactive amine compound as a hardener, it is a two-packtype characterized in that an epoxy resin and the hardener component aremixed together right before use of the two-pack type. However, since thetwo-pack epoxy resin composition requires such operations as measuringand mixing, it has poor workability. Further, due to complication of theoperations, the two-pack epoxy resin composition also has problems suchas a measuring error and inadequate mixing. In addition, the two-packepoxy resin composition also has a problem that time in which it can beused is limited since a chemical reaction in the two-pack type isinitiated by mixing.

Under the circumstances, a variety of studies on a one-pack epoxy resincomposition have been made, and a number of techniques for a one-packepoxy resin composition using a moisture hydrolyzable latent hardener,notably a ketimine compound and an oxazolidine compound, are known. Inparticular, from an industrial standpoint, a variety of techniques for aone-pack epoxy resin composition using a ketimine compound obtained frommethyl isobutyl ketone as a carbonyl compound have been disclosed.

The ketimine compound and the oxazolidine compound are well-known as alatent hardener for an epoxy resin and an isocyanate-terminated urethanepolymer. Hereinafter, a reaction mechanism of a composition comprisingthe ketimine compound or oxazolidine compound as a latent hardener andan epoxy resin will be described. Firstly, as a first reaction, theketimine compound reacts with moisture in the air and is hydrolyzed soas to produce a primary amine compound having active hydrogen. Theoxazolidine compound reacts with moisture in the air so as to produce asecondary amino alcohol. Thus, the first reaction is a process in whichthe latent hardener is hydrolyzed by moisture. Subsequently, as a secondreaction, the produced amine compound having active hydrogen reacts withthe epoxy resin, and by this mechanism, the epoxy resin composition iscured. Hence, the second reaction is a process in which the hydrolyzedlatent hardener chemically reacts with the epoxy resin. That is, thereaction mechanism of the composition comprising the latent hardener andthe epoxy resin is a two-step reaction comprising the reaction of thelatent hardener with moisture and the reaction of the amine compoundwith the epoxy resin. In these two processes, the most important pointswith respect to the compositions comprising these latent hardeners andthe epoxy resin are that (1) the quicker the hydrolysis of the latenthardener such as the ketimine compound proceeds, quicker-curability canbe obtained and that (2) the higher the reactivity of the amine compoundresulting from the hydrolysis, the more easily physical properties suchas quick curability and high strength are obtained. However, when aketimine compound which is hydrolyzed quickly is used, the ketiminecompound is liable to be hydrolyzed during production or storage of theone-pack epoxy resin, so that it becomes difficult to obtain goodstorage stability. Hence, it was the limitation of the prior art that itcould not help but relying on means using a ketimine compound obtainedfrom an amine compound having high reactivity with the epoxy resin andhaving low hydrolyzability, in consideration of storage stability. Thus,since there is a dilemma that an improvement in quick curability causesimpairment of storage stability, a technique of achieving practicalquick curability and practical storage stability simultaneously in thecomposition comprising the ketimine compound and the epoxy resin is notyet found at all.

Meanwhile, recently, a technique of improving storage stability by useof a specific ketimine compound obtained from a carbonyl compound havingsteric hindrance is disclosed in WO98/31722. The specific ketiminecompound has low hydrolyzability since water hardly makes contact with asite showing hydrolyzability due to its steric structure. Therefore, theketimine compound has the conventional problem that although it canimpart good storage stability, it fails to impart good curing propertiessuch as quick curability. That is, when the specific ketimine compoundis used, there arises a problem that curing of an epoxy resincomposition proceeds slowly, so that initial adhesive strength andmechanical strength are slow to become in effect. It takes long-timecuring to attain practicable physical properties, so that the ketiminecompound is practically unsatisfactory. Consequently, even thistechnique is not a technique capable of achieving practical curingproperties and practical storage stability simultaneously. That is, itis a technical means which is an extension of the prior art.

Thus, if a composition having excellent storage stability and excellentcuring properties is found out of compositions comprising a ketiminecompound or oxazolidine compound as a latent hardener and an epoxyresin, it becomes a fundamental technique for an adhesive, puttymaterial, paint, coating material and potting material using them, sothat usefulness of such a composition in industry is significantlyimproved.

Under the circumstances, an object of the present invention is toprovide a one-pack moisture curable epoxy resin composition which can becured at room temperature, shows balanced contradictory properties,i.e., has significantly excellent storage stability without impairingcurability, and also has excellent deep curability.

DISCLOSURE OF THE INVENTION

The present inventors have made intensive studies so as to achieve theabove object. As a result, they have found that a one-pack moisturecurable epoxy resin composition comprising a vinyl carboxylate compoundor a silane compound having an epoxy group and a ketimine compound or anoxazolidine compound shows significantly excellent storage stability.They have also found that when a vinyl carboxylate compound or a silylcompound having an epoxy group is added to a one-pack moisture curableepoxy resin composition containing a ketimine compound or oxazolidinecompound which is hydrolyzed by moisture in the air so as to produce anamine compound, storage stability can be further improved withoutimpairing curing properties such as rises of adhesive property andmechanical strength. Further, they have found that an epoxy resincomposition containing a silyl compound having an epoxy group hasexceptionally excellent deep curability. It has been confirmed that thetechnique is a function of not inhibiting having but achieving the abovepractical curing properties and storage stability simultaneously. Morespecifically, although there has been a dilemma in the prior art thatstorage stability must be improved at the sacrifice of curingproperties, the above technique has been confirmed to be a technique foreliminating the dilemma.

That is, the invention of the present application is based on an effectthat the epoxy-group-containing silyl compound added to the above epoxyresin composition removes water entering the composition during itsproduction or storage in a container before the ketimine compound oroxazolidine compound reacts with the water so as to allow the ketiminecompound or oxazolidine compound to exist stably and an effect that theepoxy group reacts with the amine compound so as to improve storagestability without impairing physical properties of a cured product.Further, the invention of the present application is also based on aneffect that the vinyl carboxylate compound added to the above epoxyresin composition blocks active hydrogen of the amine compound resultingfrom hydrolysis of the ketimine compound or oxazolidine compound duringstorage of the composition in a container so as to further improvestorage stability. These two techniques are techniques for achieving thedesired object of having practical curing properties and excellentstorage stability. The techniques act on the different reactionsconstituting the two-step reaction of the ketimine compound oroxazolidine compound with the epoxy resin, and each of the techniques isstill effective alone in improving storage stability. Further, since thetechniques exhibit their effects of improving storage stability in thedifferent reactions steps without offsetting the effects, storagestability is further improved by using these two techniquessimultaneously.

Based on these findings, the present inventors have widely studied typesof compounds having such properties, amounts of these compounds to bemixed with the epoxy resin, and techniques of synthesizing thesecompounds. As a result, they have succeeded in development of a one-packmoisture curable epoxy resin composition which can be used without anyproblems even after long-time storage without impairing the speeds ofrises of initial adhesive strength, adhesive strength and mechanicalstrength and have completed the present invention.

As means of the present invention for achieving the above object, afirst invention is a one-pack moisture curable epoxy resin compositioncomprising:

-   one or two or more compounds selected from the group consisting of a    vinyl carboxylate compound represented by the following chemical    formula (1) and a silyl compound represented by the following    chemical formula (2) which has an epoxy group in an organic group,    one or two or more compounds selected from the group consisting of a    ketimine compound represented by the following chemical formula (4)    which is obtained by reaction of a carbonyl compound represented by    the following chemical formula (3) with an amine compound having a    primary amino group and an oxazolidine compound represented by the    following chemical formula (5) which is obtained by dehydration    condensation of a carbonyl compound and an aminoalcohol compound,    and an epoxy resin:

wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom or an organic groupand they may be the same or different, and

-   n is an integer of 1 or more,

wherein R₅ and R₆ are each an alkyl group and they may be the same ordifferent,

-   R₇ is an organic group having an epoxy group,-   n is an integer of 1 to 3,

wherein R₈ and R₉ are each an alkyl group and they may be the same ordifferent,

wherein R₁₀ is a residue excluding a primary amino group of an aminecompound,

-   R₈ and R₉ are each an alkyl group and they may be the same or    different, and-   n is an integer of 1 or more, and

wherein R₁₁, R₁₂, R₁₃, R₁₄ and R₁₅ are each a hydrogen atom or anorganic group.

A silyl compound having an epoxy group in the present invention is acompound represented by the above chemical formula (2) which has ahydrolyzable alkoxysilyl group comprising an Si—O bond and an epoxygroup. The alkoxysilyl site causes a dealcoholization reaction withwater, thereby consuming the water. The silyl compound reacts with andconsumes a small amount of water entering the composition system duringstorage before the ketimine compound reacts with the water so as toprevent hydrolysis of the ketimine compound. Since it is prevented thatthe ketimine compound is hydrolyzed during storage and produces an aminecompound, storage stability is improved. The silyl compound also reactswith water quickly upon use of the adhesive composition. In that case,however, since a large amount of water enters the system, the ketiminecompound represented by the above chemical formula (4) in the presentinvention also reacts with water quickly due to its highhydrolyzability. That is, this implies that the composition of thepresent invention does not require long-time curing so as to obtainpracticable physical properties.

Further, in such a silyl compound, the epoxy group also acts as areactive site in addition to the hydrolyzable Si—O bond. Hence, it hasmore crosslinkable sites in a molecule. Accordingly, a more complicatedcrosslinked structure is formed more quickly, and curing occurs in adeeper portion even after curing over a predetermined time period. Thatis, this implies that it has excellent deep curability. The technique isa function of not inhibiting having but achieving the above practicalcuring properties and storage stability simultaneously.

A vinyl carboxylate compound used in the present invention is a compoundrepresented by the above chemical formula (1) which has a C═C—O—C═Obond. The site reacts with an amine compound so as to produce an amidecompound. The vinyl carboxylate compound reacts with a small amount ofamine compound resulting from hydrolysis of the ketimine compound oroxazolidine compound by a small amount of water entering the compositionsystem during storage so as to produce an amide compound having lowactivity with the epoxy resin, thereby improving storage stability. Thevinyl carboxylate compound also reacts with the amine compound upon useof the adhesive composition. However, since its amount is small whereasthe amount of the amine compound resulting from the hydrolysis is large,it has no influence on curing properties. That is, this implies thatstorage stability can be improved without impairing curing propertiesupon use.

By incorporating the above vinyl carboxylate compound into the one-packepoxy resin composition, storage stability could be improveddramatically.

A ketimine compound used in the present invention is a compoundrepresented by the above chemical formula (4) which has a hydrolyzableC═N double bond. The site reacts with water so as to be hydrolyzed intoan amine compound having a primary amino group and a carbonyl compoundhaving two same or different alkyl groups. In the one-pack moisturecurable epoxy resin composition, the produced amine compound reacts withthe epoxy resin so as to cure the composition.

An oxazolidine compound used in the present invention is a hydrolyzablecyclic compound represented by the above chemical formula (5) which hasan O atom and an N atom on the same carbon. The site reacts with waterso as to be hydrolyzed into a secondary aminoalcohol and a carbonylcompound having two same or different alkyl groups. In the one-packmoisture curable epoxy resin composition, the produced amine compoundreacts with the epoxy resin so as to cure the composition.

A second invention is a one-pack moisture curable epoxy resincomposition comprising:

-   a vinyl carboxylate compound represented by the above chemical    formula (1),-   one or two or more compounds selected from the group consisting of a    ketimine compound represented by the above chemical formula (4)    which is obtained by reaction of a carbonyl compound represented by    the above chemical formula (3) with an amine compound having a    primary amino group and an oxazolidine compound represented by the    above chemical formula (5) which is obtained by dehydration    condensation of a carbonyl compound and an aminoalcohol compound,    and an epoxy resin.

A third invention is a one-pack moisture curable epoxy resin compositioncomprising a silyl compound represented by the above chemical formula(2) which has an epoxy group in an organic group, a ketimine compoundrepresented by the above chemical formula (4), and an epoxy resin.

A fourth invention is a one-pack moisture curable epoxy resincomposition comprising:

-   a vinyl carboxylate compound represented by the above chemical    formula (1),-   one or two or more compounds selected from the group consisting of a    silyl compound represented by the following chemical formula (6) and    a silyl compound represented by the following chemical formula (7),-   a ketimine compound represented by the above chemical formula (4)    which is obtained by reaction of a carbonyl compound represented by    the above chemical formula (3) with an amine compound having a    primary amino group, and an epoxy resin:

wherein R₁₆, R₁₇, R₁₈ and R₁₉ are each an alkyl group and they may bethe same or different, and

-   n is an integer of 1 or more, and

wherein R₂₀ and R₂₁ are each an alkyl group and they may be the same ordifferent,

-   R₂₂ is an organic group, and-   n is an integer of 1 to 3.

Since these silyl compounds have hydrolyzable alkoxysilyl groups, theycan suppress reaction of the ketimine compound or oxazolidine compoundwith water entering at the time of production or during storage. Thatis, the composition of the present invention is a one-pack moisturecurable epoxy resin composition which does not require long-time curingso as to exhibit satisfactory strength.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described indetail.

A vinyl carboxylate compound used in the present invention may be anycompound represented by the following chemical formula (1) which has avinyl carboxylate group. Specific examples of the compound representedby the following chemical formula (1) include vinyl acetate, vinylbutyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate,vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octoate, vinyl monochloroacetate, divinyl adipate,vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, andvinyl cinnamate. It is needless to say that the vinyl carboxylate usedin the present invention is not limited to these vinyl carboxylates andtwo or more vinyl carboxylates may be used in combination.

wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom or an organic groupand they may be the same or different, and

-   n is an integer of 1 or more.

These vinyl carboxylates have high reactivity with an amine compound.Therefore, an amine compound resulting from hydrolysis by water enteringduring storage reacts with the vinyl carboxylate before reacting with anepoxy resin so as to prevent an increase in viscosity which is a problemin terms of quality.

A silyl compound used in the present invention and having an epoxy groupin an organic group may be any compound represented by the followingchemical formula (2) which has an epoxy group and an alkoxysilyl groupin a molecule. Specific examples thereof includeγ-glycidoxypropyltrimethoxysilane represented by the following chemicalformula (8) and γ-glycidoxypropyltriethoxysilane represented by thefollowing chemical formula (9). Commercial products thereof areexemplified by KBM403 and KBE403 (products of SHIN-ETSU CHEMICAL CO.,LTD.), respectively, but are not limited to them. It is needless to saythat compounds represented by the following chemical formula (2) may beused in combination of two or more and may also be used in combinationwith a silyl compound represented by the above chemical formula (6) or(7):

wherein R₅ and R₆ are each an alkyl group and they may be the same ordifferent,

-   R₇ is an organic group having an epoxy group, and-   n is an integer of 1 to 3, and

A ketimine compound used in the present invention is a hydrolyzablecompound represented by the following chemical formula (4) which has adouble bond between a carbon atom and a nitrogen atom. The ketiminecompound is a compound obtained by reaction of a carbonyl compound inwhich same or different alkyl groups are bonded to a carbon atom in acarbonyl group with an amine compound having a primary amino group. Theketimine compound may be any compound having a structure represented bythe chemical formula (4). Specific examples thereof includeN,N′-di(1,3-dimethylbutylidene)-1,3-bisaminomethylcyclohexanerepresented by the following chemical formula (10) andN,N′-di(1,3-dimethylbutylidene)-meta-xylylene diamine represented by thefollowing chemical formula (11). These are a dehydration condensate of1,3-bisaminomethylcyclohexane and methyl isobutyl ketone and adehydration condensate of meta-xylylene diamine and methyl isobutylketone, respectively.

wherein R₁₀ is a residue excluding a primary amino group of an aminecompound,

-   R₈ and R₉ are each selected from the group consisting of alkyl    groups and they may be the same or different, and-   n is an integer of 1 or more, and

A carbonyl compound which is used as a raw material of the ketiminecompound used in the present invention may be any carbonyl compoundrepresented by the following chemical formula (3) in which same ordifferent alkyl groups are bonded to a carbon atom in a carbonyl group.Specific examples thereof include acetone, methyl ethyl ketone, methylisobutyl ketone, methyl isopropyl ketone, and methyl isopentyl ketone.

wherein R₈ and R₉ are each an alkyl group and they may be the same ordifferent.

An amine compound which is used as a raw material of the ketiminecompound used in the present invention may be any compound having aprimary amino group. Specific examples thereof include, but not limitedto, ethylene diamine, diethylene triamine,1,3-bisaminomethylcyclohexane, norbornane diamine, meta-xylylenediamine, isophorone diamine, bis(4-aminocyclohexyl)methane, a polyaminehaving a polyoxylene skeleton,N-β(aminoethyl)γ-aminopropyltrimethoxysilane,N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane,γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane. Anamine compound having two or more primary amino groups in a molecule ispreferred since excellent mechanical strength is obtained.

The ketimine compound may be produced by any production method. Forexample, it can be produced by mixing the above carbonyl compound withthe above amine compound in the absence of a solvent or in the presenceof a nonpolar solvent (such as hexane, cyclohexane, toluene or benzene),subjecting the mixture to reflux under heating, and removing producedwater by azeotropy. As the carbonyl compound and amine compound used asraw materials, one or two or more compounds selected from the groupconsisting of a variety of carbonyl compounds and one or two or morecompounds selected from the group consisting of a variety of aminecompounds may be used.

A specific oxazolidine compound used in the present invention is ahydrolyzable compound represented by the following chemical formula (5)which has an N atom and an O atom on the same carbon. The oxazolidinecompound is a compound obtained by reaction of a carbonyl compoundhaving same or different alkyl groups bonded to a C atom in a carbonylgroup with a secondary aminoalcohol compound. The specific oxazolidinecompound may be any compound having a structure represented by thechemical formula (5):

wherein R₁₁, R₁₂, R₁₃, R₁₄ and R₁₅ are each a hydrogen atom or anorganic group.

The carbonyl compound which is used as a raw material of the oxazolidinecompound used in the present invention may be any carbonyl compoundrepresented by the following chemical formula (3) which has same ordifferent alkyl groups bonded to a carbon atom in a carbonyl group.Specific examples of such a carbonyl compound include acetone, methylethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, methylisopentyl ketone, diethyl ketone, dipropyl ketone, dibutyl ketone, ethylpropyl ketone, and ethyl butyl ketone.

wherein R₈ and R₉ are each an alkyl group and they may be the same ordifferent.

The aminoalcohol which is used as a raw material of the oxazolidinecompound used in the present invention may be any compound having asecondary ethanolamine structure. Specific examples thereof include, butnot limited to, N-methylethanolamine, N-ethylethanolamine,N-propylethanolamine, N-ethyl-2-methylethanolamine, and diethanolamine.Of these, N-methylethanolamine and N-ethylethanolamine are preferredsince they have high reactivity with an epoxy resin.

The oxazolidine compound may be produced by any production method. Forexample, it can be produced by mixing the above carbonyl compound withthe above aminoalcohol compound in the absence of a solvent or in thepresence of a nonpolar solvent (such as hexane, cyclohexane, toluene orbenzene), subjecting the mixture to reflux under heating, and removingproduced water by azeotropy. As the carbonyl compound and aminoalcoholcompound used as raw materials, one or two or more compounds selectedfrom the group consisting of a variety of carbonyl compounds and one ortwo or more compounds selected from the group consisting of a variety ofaminoalcohol compounds may be used.

Further, it is needless to say that two or more of the above ketiminecompounds and the above oxazolidine compounds may be used in theone-pack epoxy resin composition. In addition, as long as curingproperties and storage stability are not impaired, other latenthardeners may also be used.

The epoxy resin may be any epoxy resin having an epoxy group which iscapable of reacting with the amine compound resulting from hydrolysis ofthe ketimine compound or oxazolidine compound at the time of its use.Illustrative examples of the epoxy resin include a biphenyl epoxy resin,a bisphenol-A epoxy resin, a bisphenol-F epoxy resin, a bisphenol-ADepoxy resin and a bisphenol-S epoxy resin which are obtained by reactingbiphenyl, bisphenol A, bisphenol F, bisphenol AD and bisphenol S withepichlorhydrin, epoxy resins resulting from hydrogenation or brominationof these epoxy resins, a glycidyl ester epoxy resin, a novolac epoxyresin, an urethane-modified epoxy resin having an urethane bond, anitrogen-containing epoxy resin resulting from epoxidation ofmeta-xylene diamine or hydantoin, and a rubber-modified epoxy resincontaining a polybutadiene or NBR. The epoxy resin is not limited tothese epoxy resins, and two or more epoxy resins may be used incombination.

The silyl compound used in the present invention may be any compoundrepresented by the following chemical formula (6) or (7) which has analkoxysilyl group. Specific examples of the compound represented by thefollowing chemical formula (6) include monomers such astetramethoxysilane, tetraethoxysilane and tetrabutoxysilane, andpolymers thereof. Specific examples of the compound represented by thefollowing chemical formula (7) include silane coupling agents havingorganic groups such as an alkyl group, a vinyl group, an epoxy group, anisocyanate group and a ketimine group. Specific examples of the silanecoupling agents include dimethyldimethoxysilane, methyltrimethoxysilane,methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane,γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane,γ-glycidoxypropylmethyldiethoxysilane, andγ-isocyanatepropyltriethoxysilane. It is needless to say that the silanecoupling agents are not limited to those enumerated above and two ormore silane coupling agents may be used in combination.

wherein R₁₆, R₁₇, R₁₈ and R₁₉ are each an alkyl group and they may bethe same or different, and

-   n is an integer of 1 or more, and

wherein R₂₀ and R₂₁ are each an alkyl group and they may be the same ordifferent,

-   R₂₂ is an organic group, and-   n is an integer of 1 to 3.

As for the amount of the vinyl carboxylate based on the epoxy resin inthe present invention, it is preferably 1 to 30 mol % per mol of anepoxy group. When the amount is larger than the above range, the vinylcarboxylate hinders reaction with the epoxy resin by reacting with theamine compound produced from the ketimine compound or oxazolidinecompound. When the amount is smaller than the above range, the vinylcarboxylate cannot fully react with the amine compound resulting fromhydrolysis of the ketimine compound or oxazolidine compound by a smallamount of water entering the composition during storage, so that storagestability cannot be improved. The amount preferably falls within theabove range since practical storage stability can be obtained. Theamount is more preferably 5 to 15 mol % since more ideal storagestability can be obtained.

As for the amount of the silyl compound represented by the abovechemical formula (2), (6) or (7) based on the epoxy resin used in thepresent invention, it varies according to the type of silyl compound tobe used. However, it is preferred that the amount of the silyl compoundbe not smaller than 10 parts by weight based on 100 parts by weight ofthe epoxy resin. When the amount is lower than the above range, theamount of the silyl compound is too small to fully consume a smallamount of water entering the composition system during storage and tosuppress hydrolysis of the ketimine compound or oxazolidine compound, sothat practical storage stability cannot be obtained. The amountpreferably falls within the above range since practical storagestability can be obtained. The amount is more preferably not smallerthan 30 parts by weight since the most superior storage stability can beobtained.

The mixing ratio of the ketimine compound and the epoxy compound in thepresent invention is determined according to the equivalent of activehydrogen in the amine compound resulting from hydrolysis of the ketiminecompound and the equivalent of an epoxy group in the epoxy compound.That is, the equivalent of the active hydrogen in the amine compoundresulting from the hydrolysis of the ketimine compound is preferably 0.5to 2.0 times as much as the equivalent of the epoxy group. When themixing ratio is lower than the above range, the epoxy group becomesexcessive, crosslinking in a cured product does not proceedsatisfactorily, and practical mechanical strength cannot be obtained.When the mixing ratio is higher than the above range, the amine compoundresulting from the hydrolysis becomes excessive, that is, the activehydrogen becomes excessive, and in this case as well, due to the samereason, practical mechanical strength cannot be obtained. The mixingratio preferably falls within the above range since a crosslinkedstructure with practical mechanical strength can be obtained. The mixingratio is more preferably 0.8 to 1.2 times since an ideal crosslinkedstructure with better mechanical strength as an adhesive composition canbe obtained.

As for the amount of the oxazolidine compound based on the epoxycompound in the present invention, it is preferably 10 to 40 parts byweight based on 100 parts by weight of the epoxy resin having a weightper epoxide of 190. When the amount is lower than the above range, theepoxy group becomes excessive, crosslinking in a cured product does notproceed satisfactorily, and practical mechanical strength cannot beobtained. When the amount is higher than the above range, the aminecompound resulting from hydrolysis becomes excessive, that is, activehydrogen becomes excessive, and in this case as well, due to the samereason, practical mechanical strength cannot be obtained. The amountpreferably falls within the above range since a crosslinked structurewith practical mechanical strength can be obtained. The amount is morepreferably 20 to 30 parts by weight since an ideal crosslinked structurewith better mechanical strength as an adhesive composition can beobtained.

In addition to the foregoing compounds, the composition of the presentinvention may also contain a filler such as calcium carbonate ortitanium oxide, a coupling agent such as epoxysilane or vinylsilane, aplasticizer, a thixotropy imparting agent, a pigment, a dye, an ageresistor, an antioxidant, an antistatic agent, a flame retardant, anadhesion imparting agent, a dispersant, a solvent and the like in suchan amount that does not impair the effect of the present invention. Inthis case, it gives a favorable result on storage stability that theinfluence of water in the above components which may be contained isremoved as much as possible.

A production method of the composition of the present invention is notparticularly limited but is preferably produced by fully kneading itsraw materials under a nitrogen atmosphere or a reduced pressure by useof a stirrer such as a mixer. An example of the production method is asfollows. An epoxy resin is put in a closed processing furnace equippedwith a stirrer, a condenser, a heater, a low-pressure dehydrator and anitrogen current ventilator. Using the nitrogen current ventilator, amodifier or an additive is added to the epoxy resin as desired and theyare mixed uniformly under nitrogen reflux. Thereafter, one or two ormore compounds selected from the group consisting of a ketimine compoundand an oxazolidine compound are added eventually and mixed uniformly soas to obtain a one-pack moisture curable adhesive composition. Then, theone-pack moisture curable adhesive composition is put in anitrogen-substituted closed container so as to become a final product.When water is contained in the modifier or additive, the composition isliable to be cured and storage stability is liable to deteriorate duringstorage. Hence, it is preferable to remove the water from the modifieror additive in advance. The water may be removed before addition of themodifier or additive or removed by means of heating or decompressionafter they are added to the epoxy resin.

EXAMPLES

Hereinafter, the present invention will be described based on Examples.The present invention, however, shall not be limited to the Examples.

[Synthesis of Ketimine Compound]

Synthesis Example 1

142 g of 1,3-bisaminomethylcyclohexane (product of Mitsubishi GasChemical Company Inc., trade name: 1,3-BAC) and 300 g of methyl isobutylketone corresponding to 3 time mole equivalents were put in a flask and,while produced water was removed by azeotropy, they were allowed toreact for 20 hours at temperatures (120 to 150° C.) at which toluene andmethyl isobutyl ketone were refluxed. Then, excessive methyl isobutylketone and toluene were distilled out so as to obtain a ketiminecompound A.

Synthesis Example 2

A ketimine compound B was obtained in the same manner as in SynthesisExample 1 except that 154 g of norbornane diamine (product of MitsuiChemicals, Inc., trade name: NBDA) was used as an amine compound.

Example 1

100 parts by weight of epoxy resin (product of YUKA SHELL EPOXY CO.,LTD. (corporate name change: Japan Epoxy Resins), trade name: Epikote828), 40 parts by weight of heavy calcium carbonate (product of NITTOFUNKA KOGYO CO., LTD., trade name: NS100) and 80 parts by weight ofsurface-treated calcium carbonate (product of MARUO CALCIUM CO., LTD.,trade name: MS700) were heated at 100° C. under a reduced pressure of 15Torr for 2 hours and stirred and mixed until the mixture became uniform.After the mixture became uniform, it was cooled to room temperature.Then, to the mixture, 30 parts by weight of an oxazolidine compound(product of San-Apro Ltd., trade name: MS-PLUS) as a hardener for theepoxy resin and 6.6 parts by weight of vinyl butyrate as a stabilizerwere added, and the resulting mixture was stirred under a reducedpressure so as to obtain a one-pack moisture curable epoxy resincomposition.

Example 2

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 1 except that 40 parts by weight of epoxysilane coupling agent (product of SHIN-ETSU CHEMICAL CO., LTD., tradename: KBM403) was used in place of vinyl butyrate as a stabilizer.

Example 3

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 1 except that 45 parts by weight of theketimine compound A was used in place of the oxazolidine compound as alatent hardener.

Example 4

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 2 except that 45 parts by weight of theketimine compound A was used in place of the oxazolidine compound as alatent hardener.

Example 5

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 4 except that 6.6 parts by weight of vinylbutyrate was added as a stabilizer.

Example 6

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 5 except that the ketimine compound B was usedin place of the ketimine compound A as a latent hardener.

Example 7

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 5 except that 10 parts by weight ofoxazolidine compound as a latent hardener was added in place of reducingthe amount of the ketimine compound A as a latent hardener to 30 partsby weight.

Example 8

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 3 except that 40 parts by weight of ethylsilicate (Toshiba Silicones Co., Ltd., trade name: TSL8124) was added asa stabilizer.

Example 9

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 8 except that 13.1 parts by weight of vinyllaurate was used in place of vinyl butyrate as a stabilizer.

Comparative Example 1

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 1 except that vinyl butyrate was not used.

Comparative Example 2

A one-pack moisture curable epoxy resin composition was obtained in thesame manner as in Example 3 except that vinyl butyrate was not used.

The following tests were conducted by use of the one-pack moisturecurable epoxy resin compositions of Examples 1 to 9 and ComparativeExamples 1 and 2. The results of Examples 1 to 9 and ComparativeExamples 1 and 2 are shown in Tables 1 and 2.

TABLE 1 Ex.1 Ex.2 Ex.3 Ex.4 Ex.5 Ex.6 Epoxy Resin Epikote 828 100 100100 100 100 100 Heavy Calcium Carbonate NS100 40 40 40 40 40 40 TreatedCalcium Carbonate MS700 80 80 80 80 80 80 Oxazolidine Compound MS-PLUS30 30 Ketimine Compound A 1,3-BAC-MIBK 45 45 45 Ketimine Compound BNBDA-MIBK 45 Vinyl Ester Compound A Vinyl Butyrate 6.6 6.6 6.6 6.6 VinylEster Compound B Vinyl Laurate Ethyl Silicate TSL8124 EpoxysilaneCompound KBM403 40 40 40 40 Adhesive Property 23° C., after 7 days 5.85.6 7.5 7.9 9.2 8.9 (Mortar Bending Adhesive Cohesive Cohesive CohesiveMortar Mortar Mortar Strength) Failure Failure Failure Failure FailureFailure upper row: N/mm² Partial lower row: condition of Mortar failureFailure Deep Curability 23° C., after 7 days Good Excellent AcceptableGood Good Good Stability 20° C., after 2 Excellent Excellent ExcellentExcellent Excellent Excellent months 20° C., after 4 Excellent ExcellentGood Good Excellent Excellent months 20° C., after 6 AcceptableAcceptable Acceptable Acceptable Excellent Excellent months Ex.: ExampleAn adhesive property was measured in a mortar bending adhesive test(refer to JIS A6024 Adhesive Property) under various curing conditions.Deep Curability was measured by charging the composition into a deepcontainer without trapping air therein, allowing the composition to cureat 23° C. for 1 week, and measuring the thickness of a cured productlayer excluding the uncured composition. Stability was measured byplacing a sample in a closed cartridge and measuring its viscosity whenthe sample was stored at various temperature conditions.

TABLE 2 Ex.7 Ex.8 Ex.9 C.Ex.1 C.Ex.2 Epoxy Resin Epikote 828 100 100 100100 100 Heavy Calcium Carbonate NS100 40 40 40 40 40 Treated CalciumCarbonate MS700 80 80 80 80 80 Oxazolidine Compound MS-PLUS 10 30Ketimine Compound A 1,3-BAC-MIBK 30 45 45 45 Ketimine Compound BNBDA-MIBK Vinyl Ester Compound A Vinyl Butyrate 6.6 6.6 Vinyl EsterCompound B Vinyl Laurate 13.1 Ethyl Silicate TSL8124 40 40 EpoxysilaneCompound KBM403 40 Adhesive Property 23° C., after 7 days 8.0 6.5 6.15.5 6.4 (Mortar Bending Adhesive Mortar Cohesive Cohesive CohesiveCohesive Strength) Failure Failure Failure Failure Failure upper row:N/mm² Partial Partial Partial lower row: condition of Mortar MortarMortar failure Failure Failure Failure Deep Curability 23° C., after 7days Good Acceptable Acceptable Good Acceptable Stability 20° C., after2 Excellent Excellent Excellent Unacceptable Unacceptable months 20° C.,after 4 Excellent Excellent Excellent Unacceptable Unacceptable months20° C., after 6 Excellent Excellent Excellent Unacceptable Unacceptablemonths Ex.:Example, C.Ex.: Comparative Example An adhesive property wasmeasured in a mortar bending adhesive test (refer to JIS A6024 AdhesiveProperty) under various curing conditions. Deep Curability was measuredby charging the composition into a deep container without trapping airtherein, allowing the composition to cure at 23° C. for 1 week, andmeasuring the thickness of a cured product layer excluding the uncuredcomposition. Stability was measured by placing a sample in a closedcartridge and measuring its viscosity when the sample was stored atvarious temperature conditions.(Adhesive Property)

An adhesive property was measured in accordance with JIS A6024 (refer toadhesive property) of a mortar bending adhesive test under variouscuring conditions. That is, it was measured in accordance with astandard condition (curing at 23° C. for 7 days) of an adhesive strengthtest in JIS A6024 (injection epoxy resin for construction repairing).Its unit was N/mm², and a condition of failure at that time was shown.

(Deep Curability)

The one-pack moisture curable epoxy resin composition was charged into adeep container without trapping air therein and allowed to cure at 23°C. for 1 week. The thickness of a cured product layer excluding theuncured composition was measured. The thickness of the cured productlayer was compared and rated on the following four-rank scale of“Excellent”, “Good”, “Acceptable” and “Unacceptable”.

-   Excellent: 2.0≦Thickness (mm) of cured product after cured at 23° C.    for 7 days.-   Good: 1.0≦Thickness (mm) of cured product after cured at 23° C. for    7 days<2.0-   Acceptable: 0.5≦Thickness (mm) of cured product after cured at    23° C. for 7 days<1.0-   Unacceptable: Thickness (mm) of cured product after cured at 23° C.    for 7 days<0.5

To rate the characteristic value of the deep curability in the presentinvention, a characteristic value rated as “Excellent” is the mostexcellent from a practical standpoint, followed by one rated as “Good”.A characteristic value rated as “Acceptable” is inferior to those ratedas “Excellent” and “Good” but still has practicability. However,“Unacceptable” represents a characteristic value which is the mostinferior and lacks practicability.

(Stability)

Stability was measured by placing a sample in a closed cartridge andmeasuring its viscosity when stored at various temperature conditions.That is, the one-pack moisture curable epoxy resin composition wasfilled and sealed in the cartridge and left to stand at 23° C. forvarious time periods, and then its viscosity was measured. Then,stability was compared with its viscosity immediately after preparationand rated on the following four-rank scale of “Excellent”, “Good”,“Acceptable” and “Unacceptable”. The viscosity was measured at 23° C. byuse of a BH-type viscometer at 10 r/min.

-   Excellent: (viscosity after left to stand)/(viscosity immediately    after preparation)≦1.5-   Good: 1.5<(viscosity after left to stand)/(viscosity immediately    after preparation)≦2-   Acceptable: 2<(viscosity after left to stand)/(viscosity immediately    after preparation)≦3-   Unacceptable: 3<(viscosity after left to stand)/(viscosity    immediately after preparation)

To rate the characteristic value of the stability in the presentinvention, a characteristic value rated as “Excellent” is the mostexcellent from a practical standpoint, followed by one rated as “Good”.A characteristic value rated as “Acceptable” is inferior to those ratedas “Excellent” and “Good” but still has practicability. However,“Unacceptable” represents a characteristic value which is the mostinferior and lacks practicability.

It is obvious from comparison of Examples 1 and 2 with ComparativeExample 1 that the one-pack moisture curable epoxy resin compositions ofthe Examples show adhesive properties equal to that of the one-packmoisture curable epoxy resin composition of the Comparative Example.Further, it is understood that since the one-pack moisture curable epoxyresin compositions of the Examples show better storage stability thanthe one-pack moisture curable epoxy resin composition of the ComparativeExample, only storage stability is improved without impairing theadhesive properties.

Further, it is obvious from comparison of Examples 3 to 9 withComparative Example 2 that the one-pack moisture curable epoxy resincompositions of the Examples show adhesive properties which are equal toor better than that of the one-pack moisture curable epoxy resincomposition of the Comparative Example. Further, it is understood thatsince the one-pack moisture curable epoxy resin compositions of theExamples show better storage stability than the one-pack moisturecurable epoxy resin composition of the Comparative Example, only storagestability is improved without impairing the adhesive properties. Inaddition, as is obvious from Example 5 to 7, by concurrent use of thevinyl carboxylate and the epoxysilane as stabilizers, storage stabilityand inner curability can be improved without impairing curingproperties.

POSSIBILITY OF INDUSTRIAL UTILIZATION

As described above, the one-pack moisture curable epoxy resincomposition according to the present invention is a room-temperaturecurable adhesive composition which has balanced contradictoryproperties, i.e., improving storage stability significantly withoutimpairing quick curability. Accordingly, the one-pack moisture curableepoxy resin composition according to the present invention is suitablefor being effectively used in applications in which a conventionaltwo-pack epoxy resin has been used such as an adhesive, putty material,paint, coating material and potting material using the composition.

1. A one-pack moisture curable epoxy resin composition comprising: (a) avinyl carboxylate compound represented by the following chemical formula(1), (b) one or two or more compounds selected from the group consistingof a ketimine compound represented by the following chemical formula (4)which is obtained by reaction of a carbonyl compound represented by thefollowing chemical formula (3) with an amine compound having a primaryamino group, and an oxazolidine compound represented by the followingchemical formula (5) which is obtained by dehydration condensation of acarbonyl compound and an aminoalcohol compound, and (c) an epoxy resin:

wherein R₁, R₂, R₃ and R₄ are each a hydrogen atom or an organic groupand they may be the same or different, and n is an integer of 1 or more,

wherein R₈ and R₉ are each an alkyl group and they may be the same ordifferent,

wherein R₁₀ is a residue excluding a primary amino group of an aminecompound, R₈ and R₉ are each an alkyl group and they may be the same ordifferent, and n is an integer of 1 or more, and

wherein R₁₁, R₁₂, R₁₃, R₁₄ and R₁₅ are each a hydrogen atom or anorganic group.